https://leetcode.cn/problems/binary-search/
class Solution {
public:
    int search(vector<int>& nums, int target) {
        int left=0,right=nums.size()-1;
        
        while(left<=right)
        {
            int mid=(left+right)/2;
            if(nums[mid]==target)
                return mid;
            else if(nums[mid]<target)
                left=mid+1;
            else
                right=mid-1;
        }
        return -1;
    }
};